The present invention relates to a method for handling (in particular, transmitting) encrypted user data objects which are provided by a data provisioning component and transmitted to a telecommunications device such as, for example, a mobile phone. Specifically, the present invention relates to a method which enables a user of the telecommunications device to download different rights or rights objects from the data provisioning component to the telecommunications device in return for an appropriate charge.
A method or, as the case may be, a service for reliable and accountable downloading of user data objects to a telecommunications device, in particular in the embodiment of a mobile radio device or mobile phone, in a data communications network is currently under discussion. In a proposed scheme, the downloading of the user data objects to the mobile radio device is intended to be implemented via a protocol specified by the WAP Forum (WAP: Wireless Application Protocol) or an Internet protocol (e.g., Hypertext Transfer Protocol: HTTP). The downloading service is specified here in such a way that a user with an application program which is available on the mobile radio device and which is referred to as a download client is to be allowed to download any user data objects which are provided by one or more data provisioning components, particularly servers or, as the case may be, download servers of service providers or content providers in the data communications network. A possible embodiment of the service makes provision for a downloadable user data object to be provided with restrictions in relation to its usage by the user of the mobile radio device. This can be used, for example, to restrict the number of uses of the user data object or also the usage period. The practical implementation is effected by the description of the restrictions using a suitable language such as, for example, ODRL (Open Digital Rights Expression Language), whereby the download client or another special application, called a DRM agent, receives the rights description for management of the rights associated with a (digital) user data object (DRM: Digital Rights Management), evaluates it, stores it in a protected memory area that is not accessible to the user on the mobile radio device and, in response to a request by the user to use the object, grants or does not grant such rights in accordance with the rights description. The user data object itself can be protected against unauthorized access either by being stored in encrypted form in a freely accessible memory area on the mobile radio device or by being managed by a special application, such as the DRM agent, which does not allow any unauthorized access to the object by the user.
According to a variant specified by the WAP Forum for the management of DRM-protected contents, a user data object provided by a data provisioning component is encrypted and finally packed for transport and storage onto a telecommunications device such as a mobile radio device in a so-called container file or a so-called container object (which, for example, has been assigned the data type or content type “Application/VND.OMA.DRM.Content”). Through the use of a service for reliable downloading of content by a data provisioning component (content download), the encrypted user data object is packed in the container object and transmitted to the telecommunications device using WAP protocols (such as, for example, the WSP: Wireless Session Protocol) or Internet protocols (such as, for example, the HTTP). A so-called rights object is transmitted to the telecommunications device separately from the encrypted user data object; for example, via a WAP push. The rights object contains a description of the rights granted to the user for using the encrypted user data objects, a reference to the container object which enables the rights object to be assigned to the corresponding container object, and a key by which the encrypted user data object can be decrypted so that it subsequently may be used. A special device or application, which may be the above-mentioned DRM agent, is necessary on the telecommunications device, such as the mobile radio device, in order to use the combination of the encrypted user data object packed in the container object and the rights object. After the transmission of the rights object to the telecommunications device, the rights object is transferred directly to the DRM agent which is responsible for the management and safekeeping of the secret; namely, the key for decrypting the encrypted user data object. In practice, the DRM agent stores the rights object on the telecommunications device and protects it against unauthorized access by other applications or users. The first step when an encrypted user data object is to be used is that the DRM agent is activated.
The latter searches for a rights object that matches the container object in the memory area managed by it in the telecommunications device on the basis of the identification contained in the container object and also in the rights object, checks whether rights can be granted for the requested usage type (such as, for example, “playing back” music data or “displaying” image data, etc.) and decrypts the user data object using the key from the rights object if the rights can be granted. Pursuant to the above described method, wherein an encrypted user data object and a rights object separate therefrom can be used, the value of digital data is no longer represented by the encrypted user data object or the container object itself, but rather by the rights object and the key contained therein, without which, of course, the encrypted user data object cannot be used. Thus, in this case the encrypted user data objects can be stored in packed form in the container objects on the telecommunications device and be freely accessible. This also allows encrypted user data objects, packed in container objects, to be forwarded by a user to one or more other users, a process referred to as “superdistribution”.
In order to make the encrypted user data object contained in a forwarded container object usable, an individual user must download a suitable rights object from a rights provider that may be identical to the content provider providing a specific user data object.
The method just described, in which in order to make user data objects usable it is necessary firstly to download a container object containing an encrypted user data object, and secondly to download a rights object from an identical or from different data provisioning component(s), does, however, have the disadvantage that before downloading a rights object a user has no way to check whether the rights object offered, for example, by an arbitrary provider does in fact enable the use of the encrypted user data object which is already present, stored in the container object, on the user's own telecommunications device; i.e., whether the offered rights object includes, for example, the right key for decrypting the encrypted user data object contained in the container object. A further disadvantage is that a user without a purchased or downloaded rights object has no way whatsoever to check whether the encrypted user data object received by his or her telecommunications device or even the entire container object is undamaged.
Accordingly, the present invention seeks to provide a method by which a user is rendered capable of checking the integrity or, as the case may be, usability of an encrypted user data object stored on his or her telecommunications device.